Pressure-reducing valve for breathing apparatus



United States Patent [72] Inventor: Leszek Suchy Gdansk, Poland [21]Application No.: 687,763

[22] Filed: Dec. 4,1967

[45] Patented: Aug. 4, 1970 [73] Assi'gnee: Zaklady MechanikiPrecyzjnej- Przedziebiorst-wo Panstwowe, Gdansk-Oliwa, Poland, 'a Corp.of Poland [32] Priority: Dec. 12,1966

[33] Poland [31] No; P117924 [54] PRESSURE-REDUCING VALVE FOR BREATHINGAPPARATUS 2 Claims, 1 Drawing Fig. 1

[52] U.S.Cl. 137/494, l37/505.18, SOS-.28, 505.12

AMBlENT ENVIRONMENT [50] Field ofSearch ..l37/505.l8,

I [56] References 011611 UNITED STATES PATENTS 2,855,950 10/1958Phillips 137/50523 3,211,175 10/1965 Replogle l37/505.28XR 3,227,1721/1966 Sims 137/505.l8XR 3,250,292 5/1966 Mollick... l37/505.283,389,796 6/1968 Flala 137/509XR Primary Examiner-Harold W. WeakleyAltorney- Karl F. Ross ABSTRACT: A pressure-reducing valve for breathingapparatus provided with a piston fitted inside a movable pistonterminating in a valve head closing the seat of the conduit feeding theair from the air cylinder, where the area of the piston equals the areaofthe throttle port ofthe seat.

BREATHING i6 APPARATUS SECOND VALVE (LUNG CONTROL) COMPRESSED -AlRCYLINDER Patented Aug. 4, 1970 3,522,818

9 10 11\ 12\ 13 14 M45 8) g /16 ZEEZEQ'TTFS SECOND VALVE (LUNG CONTROL)COMPRESSED -A\R CYLINDER Leszek SUCHY IXVENTOR.

PRESSURE-REDUCING VALVE FOR BREATHING APPARATUS BACKGROUND OF THEINVENTION The invention relates to a pressure-reducing valve of thefirst stage for a breathing apparatus provided with a two-stage pressurereducing system, which is able to maintain a constant average pressureindependently of the pressure existing in the gas cylinder.

There is known a breathing apparatus in which the compressed air comingfrom the cylinder is reduced to the breathing pressure by means of twopressure-reducing valves. The first valve reduces the high pressure ofthe air coming from the air-supply cylinder to the intermediatepressure, which mostly does not exceed 8 atmospheres (atm). The secondvalve, controlled by the lung of the user reduces this pressure to abreathing pressure. The pressure reducing valves of the first stage ofknown devices have the essential disadvantage that they do not ensure aconstant intermediate pressure, which increases as the pressure in thecylinder drops.

Simplifying the matter somewhat it may be assumed, that the increase ofthe intermediate pressure depends only on the area ofthe throttlinghole. The higher pressure ofthe air coming from the cylinder upon thevalve head of the pressurereducing valve effects a more intensiveincrease of the intermediate pressure. These variations cause variedbreathing resistances and disadvantageously .influence -the breathingcharacteristic of the device. Use of the throttling hole of small areaeliminates these disadvantages to some extent, but causes strongthrottling of the flow at high demand of the air. I

There are also known pressure-reducing valves which assure maintenanceof the constant intermediate pressure, but they are characterized bytheir complicated and not readily manufactured structure.

SUMMARY OF THE INVENTION The pressure-reducing valve according to theinvention has a simplified structure and permits use of a throttlinghole of large cross-sectional area and able to cover any demand on air,and it simultaneously secures the constant intermediate pressure,independently of the pressure in the cylinder.

The task set in order to eliminate said inconveniences is, according tothe invention, accomplished in such manner that the force actingunilaterally on the valve head and effecting the increase of the reducedintermediate pressure at decreasing pressure in the cylinder iseliminated; The valve head is relieved by a force arising from thepressure of the air penetrating through a hole made in the valve headinto the space closed by the piston, the latter being movable againstthe valve head and having an area equal to the area of thethrottlinghole, so that the valve head is in stability.

BRIEF DESCRIPTION OF THE DRAWING The pressurereducing valve is morethoroughly explained by means of an exemplary embodiment in theaccompanying drawing, the sole FIG U RE of which is a longitudinalsectional 1 view of the valve.

DESCRIPTION OF THE PREFERRED EMBODIMENT The pressure-reducing valveconsists of a valve body 1, a

' nutfastening the valve to the cylinder 3, a seat 4 with the"throttling hole, a chamber of the valve head 6 connected with apistonrod 6 and a piston 11, a spring 10 opening the valve, a

cover 'l2fof the body, a piston 16, and seals l5, l7 and 19 closing thespaces 13, 21 and a chamber 5. In the cover 12 there 'are'made ports 8leading the environmental (ambient) pres- The described design may beused for breathing apparatus destined for moving under water, as well asfor a paratus insulating the human breathing system from gases 0 theenvironment.

The mode of operation of the valve according to the invention is asfollows:

Before supplying the compressed air from the cylinder, the pressure ofthe spring 10 upon the piston 11 holds the valve head 6 open. Afterinflux, the air flows from the cylinder through the conduit 2 and thechamber 5 to the conduit 20, which leads the air to the breathingapparatus. The air penetrates also through the hole l8 and the slot 14to the space 13 above the piston ll. As the suitable value of thereduced pressure is achieved, the pressure of the air upon the pistonIll overcomes the resistance of the spring 10, causes a shifting of thepiston, and closes the seat 4. Simultaneously through the hole 22 theair flows to the space 21 closed by the piston 16 abutting against thecover 12 of the valve body, creating thereby the fixed position of thepiston 16 in relation to the valve seat 4.

Iclaim:

I. In a breathing apparatus comprising a compressed-air tank, a firstvalve connected to said tank for producing air at a constantintermediate pressure less than that in said cylinder, a second valveconnected to said first valve for converting air at said intermediatepressure into air at breathing pressure, and a breathing deviceconnected to said second valve for supplying said air to the user, theimprovement wherein said first valve includes:

a valve body formed with an inlet connectable with said cylinder with apassage connected to said inlet, with a valve chamber communicating withsaid passage, and an outlet connected with said second valve:

means in said valve chamber forming a valve seat around said passage:

piston means axially displaceable in said body and including a valvemember engageable with said seat and movable toward and away from saidseat for blocking and unblocking communication between said passage andsaid valve chamber, said piston means defining within said body a firstcompartment expandable with movement of said valve member away from saidseat and communicating with the ambient environment, and a secondcompartment expandable with movement of said valve member toward saidseat, said valve member being provided with a port communicating withsaid passage in a blocking position of said valve member and with a boreextending in the direction of displace ment of said valve member andcommunicating with said port;

a plunger received in said bore and defining therein a piston chamberexpanding and contracting with movement of said valve member toward andaway from said seat, respectively, and communicating with said valvechamber via said port in an unblocking position of said valve member andcommunicating with said cylinder via said port in a blocking position ofsaid valve member, said valve member being formed with a further passageconnecting said valve member with said second compartment in allpositions of said valve member: and

a spring bearing upon said piston means and yieldably resistingcontraction of said first compartment.

2. The improvement defined in claim I wherein said valve body isprovided with a cap defining said compartments with said piston means,said plunger bearing against said cap, said piston means having a pistonsealingly and slidably engaging said cap, further seal means betweensaid valvemember and said valve body and between said plunger and saidvalve member, said plunger being formed in said piston chamber of saidvalve means with an effective surface area equal to that of the valveseat.

